Fixed the scroll direction bug where PageUp/PageDown were inverted:
- page_up now scrolls UP (back in time) with positive delta (+10)
- page_down now scrolls DOWN (forward in time) with negative delta (-10)
- Mouse wheel up/down also fixed with same logic (+3/-3)
The scroll logic in scroll_output() was correct (positive = scroll up),
but the key handlers in both main.py and pipeline_runner.py had
the signs inverted.
- Add scroll_offset to REPLState (max 50 lines)
- Modify _render_repl() to use manual scroll position
- Add scroll_output(delta) method for scroll control
- Add PageUp/PageDown keyboard support (scroll 10 lines)
- Add mouse wheel support via SGR mouse tracking
- Update HUD to show scroll percentage (like vim) and position
- Reset scroll when new output arrives
- Add tests for scroll functionality
- Add help text for add_stage, remove_stage, swap_stages, move_stage commands
- Implement _cmd_add_stage, _cmd_remove_stage, _cmd_swap_stages, _cmd_move_stage methods
- Update _handle_pipeline_mutation in main.py and pipeline_runner.py
- Fix fragile test by testing output buffer directly instead of rendered output
- Add _quit_requested flag to TerminalDisplay
- Add request_quit() method to TerminalDisplay
- Handle 'ctrl_c' key in REPL input loops in both pipeline_runner.py and main.py
- When Ctrl+C is pressed, request_quit() is called which sets the flag
- The main loop checks is_quit_requested() and raises KeyboardInterrupt
- Fix raw mode enabling to not duplicate with UI border mode
- Add REPL_USAGE.md with comprehensive guide
- Add examples/repl_demo_terminal.py example script
- Detect REPL effect in pipeline and enable interactive mode
- Enable raw terminal mode for REPL input capture
- Add keyboard input loop for REPL commands
- Add _handle_pipeline_mutation() function for pipeline control
